Rapid-freezing and cryosectioning techniques have been established for obtaining specimens from isolated, incubated rat pancreatic islets of Langerhans. The existing freezing machine was modified to function at liquid nitrogen temperatures, so that it was possible to freeze individual islets mounted with physiological buffer on a gold freezing 'hat.' The cryoultramicrotome was set up with a diamond trimming tool, a 35 degree diamond knife, and a 12-kV antistatic gun to prevent the tissue from charging during cryosectioning. With these modifications, it is now possible to obtain high-quality cryosections on which useful experiments can be performed, both in the Hitachi TEM-STEM and in the VG Microscopes field-emission STEM.